Introduction: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder amongst women of reproductive age and is associated with various metabolic perturbations. Chronic low grade inflammation has been reported to participate in the pathogenesis of metabolic syndrome. In this study we examined the effects of 8 weeks aerobic training on serum C-reactive protein level and cardiometabolic risk factors in women with polycystic ovary syndrome. Methods: This semi experimental study was carried out based on pre-test and post-test on experiment and control groups in Arak, Iran. Twenty women with polycystic ovary syndrome (aged 27.75±5.43 yr) selected and randomly divided to training and control groups (10 people for each group). Aerobic training program was performed 50-60 min/d, 3d/wk, for 2 months. Serum C-reactive protein levels (immunoturbidimetric method), body composition (bioelectrical impedance method) and metabolic parameters (enzymatic and radioimmunoassay method) were assessed before and after the training period. The collected data were analyzed using two-way ANOVA. Results: After an 8 week aerobic training, fasting glucose, insulin resistance index, total cholesterol, triglycerides and abdominal fat were significantly decreased (P<0.05). In contrast, CRP concentrations did not change significantly in response to aerobic training. Conclusion: This study demonstrated that 8 weeks of aerobic training causes an improvement in cardiometabolic risk factors in women with polycystic ovary syndrome without change in concentrations of CRP.